Expression of utrophin (dystrophin-related protein) and dystrophin-associated glycoproteins in muscles from patients with Duchenne muscular dystrophy.

We examined whether the dystrophin-associated glycoprotein complex (GPC), which serves to fix dystrophin to cell membranes, is present at the sarcolemma in Duchenne muscular dystrophy (DMD) muscles using an immunohistochemical method. Antibodies against 50DAG (A2) and 43DAG (A3a), the components of GPC, were used for the detection of GPC. We found that, although the amount of GPC was reduced in DMD muscles where utrophin but not dystrophin was distinctly present, 43DAG (A3a) was fairly heavily and 50DAG (A2) was lightly but distinctly stained on the cell surfaces. It is likely that the capability of utrophin to preserve 50DAG (A2) is less than that of dystrophin, although utrophin has been reported to bind to GPC. We also found that 43DAG (A3a) but not 50DAG (A2) was detected in the peripheral nerves where utrophin was detected. Therefore, it is likely that 43DAG (A3a) is essential for the fixation of utrophin to cell membranes, as in the case of dystrophin. 50DAG (A2) may play other important roles in the pathogenesis of DMD.